Can I adjust the gap between the rows?

Hello, first of all I really appreciate of you guys to make this fabulous application, page builder, to make awesome page.
Even I majored in Computer science, I’m not familiar with web design and your “page builder” is super helpful for me.

By the way, I tried to adjust the gap between the rows but I couldn’t find how to.
Can I adjust the gap between the rows with your apps?

At least I wanna know how to get rid of gap between rows.